The present invention is directed to an improved internal expansion coupling and sealing system that is particularly adapted for use in a tubular transmission system where high operating temperatures may be a factor or consideration in such transmission system. Further, such coupling and sealing system is especially suited to join opposing tubular members, where the ends thereof are configured to receive an annular type sealing ring which cooperates with the internal expansion member, as hereinafter defined, to effect a tight seal therebetween, even at high temperatures, such as may be associated with internal combustion type engines.
Unlike external or contraction type coupling devices, which are not effective under heat or internal pressure conditions, the present invention is directed to a unique internal coupling device that appears to thrive under pressure while coupling and sealing effectively under heat. There have been attempts by the prior art to make effective internal joint connections. For example, in U.S. Pat. No. 4,478,434 to Little, there is taught a system for coupling adjacent ends of flexible tubular members comprising an elongated open ended tube member having an O.D. that is approximately the same as the I.D. of such flexible tubular members. More particularly, such system includes a transverse slit across said open ended tube member, and a pair of aligned strap-like members having opposite ends thereof connected to said tube members on opposite sides of the slit. Threadable means, as part of the strap-like members, join the opposite ends of the tube member whereby said tube may be contracted a limited amount, or expanded.
Other internal expanding coupling means are taught in U.S. Pat. No. 3,514,135 to Cooper consisting of a split sleeve having oppositely disposed inclined longitudinal flanges which may be radially moved to expand the sleeve; U.S. Pat. No. 3,141,687 to Broberg et al for a steel band splicing strap with a threaded member to separate the strap ends; U.S. Pat. No. 3,394,951 to Crivello for a polyethylene conduit insert consisting of a pair of spaced, axially extending coupling portions and a radially outwardly extending central portion. Each of the coupling portions has a substantially cylindrical internal surface and a pair of opposed frustoconical exterior surfaces tapered at approximately 2.degree. and separated by an annular groove with the portions of the frustoconical surfaces of greatest diameter being adjacent the groove; and U.S. Pat. No. 3,269,754 to Bertling et al, a device similar in operation or function to Crivello.
U.S. Pat. No. 4,469,467 to Odill et al is directed to a flexible sealing member to be used in conjunction with other joining means to prevent water inflow into a manhole. The sealing ring consists of a pair of sealing sections joined together by a pleated section. In operation, only the sealing sections are internally supported by bands, while the pleated section is free to allow for vertical and horizontal movement of the joined components without disturbing the sealing arrangement. U.S. Pat. No. 4,346,922 to Ohtsuga et al is directed to an internally expandable, joint sealing system, that, among certain limitations, is not fully supported throughout the joint. Further, structural features are absent which allow for high temperature, high pressure applications. A further and final prior art coupling member is taught in European Patent application No. 0069098 to Anderson. Such patent teaches a low pressure, expandable, but not contractable, tubular connector for an air ventilation duct. Such joint connector is characterized by a sheet metal element bent into a circular configuration, where the overlapping ends thereof are joined together by a sealing cloth, such as rubber or other resilient materials. Around the periphery of the connector there are provided a pair of non-elastomeric sealing rings held against the periphery by steel bands. Where the ends of such bands overlap, a "weak" spot weld is provided. As taught by such patent, the steel band has a weakened spot weld at the point where the ends of the steel band overlap so that this spot weld can break when the connector is expanded by rotation of a screw.
Certain of the above prior art devices are open to the objections that they create excessive internal diameter restrictions; that they are difficult to manipulate; that they require the use of special skills and or tools to connect and disconnect; that they require strict inside pipe diameter tolerances in order to form a sealed union; that they are lacking in gasket sealing integrity under conditions of high temperature and high pressure; and that they are lacking in flexibility. The pipe coupling member of this invention overcomes those problems of the prior art, while providing a unique coupling and sealing system for high pressure, high temperature applications. The pipe coupling member when in the contracted condition can be readily inserted into the pipe ends, and when in an expanded condition exhibit a minimum restriction while providing an excellent sealed joint. The coupling can be reused in nearly its entirety. Thus, the present invention teaches an internal expansion coupling device which is more versatile than those of the prior art, and is very effective against leaks thereof by its ability to utilize the internal forces or pressures of the medium being transmitted therethrough.
The unique features hereof, particularly those revealing the use of such coupling member under high temperature and high pressure conditions will become apparent from a reading of the detailed description which follows.